diff --git a/core/config/config_helper.hpp b/core/config/config_helper.hpp
index 9de08a94ccd..18241deb49b 100644
--- a/core/config/config_helper.hpp
+++ b/core/config/config_helper.hpp
@@ -26,13 +26,14 @@ namespace gko {
 namespace config {
 
 
-#define GKO_INVALID_CONFIG_VALUE(_entry, _value)                           \
-    GKO_INVALID_STATE(_value + std::string(" is invalid for the entry ") + \
-                      _entry)
+#define GKO_INVALID_CONFIG_VALUE(_entry, _value)                            \
+    GKO_INVALID_STATE(std::string("The value >" + _value +                  \
+                                  "< is invalid for the entry >" + _entry + \
+                                  "<"))
 
 
 #define GKO_MISS_CONFIG_ENTRY(_entry) \
-    GKO_INVALID_STATE(std::string("miss the entry ") + _entry)
+    GKO_INVALID_STATE(std::string("The entry >") + _entry + "< is missing")
 
 
 /**
@@ -104,12 +105,11 @@ deferred_factory_parameter<T> parse_or_get_factory(const pnode& config,
                                                    const type_descriptor& td);
 
 template <typename T>
-inline deferred_factory_parameter<typename T::Factory> get_specific_factory(
-    const pnode& config, const registry& context, const type_descriptor& td)
+inline deferred_factory_parameter<typename T::Factory>
+parse_or_get_specific_factory(const pnode& config, const registry& context,
+                              const type_descriptor& td)
 {
     using T_non_const = std::remove_const_t<T>;
-    // static_assert(std::is_convertible<T_non_const*, LinOpFactory*>::value,
-    //               "only LinOpFactory");
     deferred_factory_parameter<typename T::Factory> ptr;
 
     if (config.get_tag() == pnode::tag_t::string) {
@@ -297,6 +297,7 @@ inline std::shared_ptr<typename Csr::strategy_type> get_strategy(
     } else if (str == "classical") {
         strategy_ptr = std::make_shared<typename Csr::classical>();
     }
+    GKO_INVALID_CONFIG_VALUE("strategy", str);
     return std::move(strategy_ptr);
 }
 
diff --git a/core/preconditioner/ic.cpp b/core/preconditioner/ic.cpp
index 366e891f22c..8ee43b30c52 100644
--- a/core/preconditioner/ic.cpp
+++ b/core/preconditioner/ic.cpp
@@ -31,12 +31,12 @@ Ic<LSolverType, IndexType>::parse(const config::pnode& config,
 
     if (auto& obj = config.get("l_solver")) {
         params.with_l_solver(
-            gko::config::get_specific_factory<const LSolverType>(obj, context,
-                                                                 td_for_child));
+            gko::config::parse_or_get_specific_factory<const LSolverType>(
+                obj, context, td_for_child));
     }
     if (auto& obj = config.get("factorization")) {
         params.with_factorization(
-            gko::config::build_or_get_factory<const LinOpFactory>(
+            gko::config::parse_or_get_factory<const LinOpFactory>(
                 obj, context, td_for_child));
     }
 
diff --git a/core/preconditioner/ilu.cpp b/core/preconditioner/ilu.cpp
index 8248739dc51..bdc2d0e14cf 100644
--- a/core/preconditioner/ilu.cpp
+++ b/core/preconditioner/ilu.cpp
@@ -34,17 +34,17 @@ Ilu<LSolverType, USolverType, ReverseApply, IndexType>::parse(
 
     if (auto& obj = config.get("l_solver")) {
         params.with_l_solver(
-            gko::config::get_specific_factory<const LSolverType>(obj, context,
-                                                                 td_for_child));
+            gko::config::parse_or_get_specific_factory<const LSolverType>(
+                obj, context, td_for_child));
     }
     if (auto& obj = config.get("u_solver")) {
         params.with_u_solver(
-            gko::config::get_specific_factory<const USolverType>(obj, context,
-                                                                 td_for_child));
+            gko::config::parse_or_get_specific_factory<const USolverType>(
+                obj, context, td_for_child));
     }
     if (auto& obj = config.get("factorization")) {
         params.with_factorization(
-            gko::config::build_or_get_factory<const LinOpFactory>(
+            gko::config::parse_or_get_factory<const LinOpFactory>(
                 obj, context, td_for_child));
     }
 
diff --git a/core/preconditioner/isai.cpp b/core/preconditioner/isai.cpp
index e6cd16b872d..b10eec36691 100644
--- a/core/preconditioner/isai.cpp
+++ b/core/preconditioner/isai.cpp
@@ -114,7 +114,7 @@ Isai<IsaiType, ValueType, IndexType>::parse(
     }
     if (auto& obj = config.get("excess_solver_factory")) {
         params.with_excess_solver_factory(
-            gko::config::build_or_get_factory<const LinOpFactory>(
+            gko::config::parse_or_get_factory<const LinOpFactory>(
                 obj, context, td_for_child));
     }
     if (auto& obj = config.get("excess_solver_reduction")) {
diff --git a/core/test/config/preconditioner.cpp b/core/test/config/preconditioner.cpp
index 5302e23249a..fadbdd4abdc 100644
--- a/core/test/config/preconditioner.cpp
+++ b/core/test/config/preconditioner.cpp
@@ -275,8 +275,6 @@ struct Jacobi
         param.with_max_block_stride(32u);
         config_map["skip_sorting"] = pnode{true};
         param.with_skip_sorting(true);
-        // config_map["block_pointers"] = pnode{{{0}, {3}, {17}}};
-        // param.with_block_pointers(gko::array<gko::int64>(exec, {0, 3, 17}));
         config_map["storage_optimization"] =
             pnode{std::vector<pnode>{pnode{0}, pnode{1}}};
         param.with_storage_optimization(gko::precision_reduction(0, 1));
diff --git a/include/ginkgo/core/factorization/cholesky.hpp b/include/ginkgo/core/factorization/cholesky.hpp
index 34cfb6aa8ed..e1799766b43 100644
--- a/include/ginkgo/core/factorization/cholesky.hpp
+++ b/include/ginkgo/core/factorization/cholesky.hpp
@@ -94,7 +94,7 @@ class Cholesky
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/ic.hpp b/include/ginkgo/core/factorization/ic.hpp
index 170297ffa0b..73afdf90464 100644
--- a/include/ginkgo/core/factorization/ic.hpp
+++ b/include/ginkgo/core/factorization/ic.hpp
@@ -106,7 +106,7 @@ class Ic : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/ilu.hpp b/include/ginkgo/core/factorization/ilu.hpp
index 785faadd65a..eb37b04b6a3 100644
--- a/include/ginkgo/core/factorization/ilu.hpp
+++ b/include/ginkgo/core/factorization/ilu.hpp
@@ -101,7 +101,7 @@ class Ilu : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/lu.hpp b/include/ginkgo/core/factorization/lu.hpp
index 9a4f2029970..6557d455577 100644
--- a/include/ginkgo/core/factorization/lu.hpp
+++ b/include/ginkgo/core/factorization/lu.hpp
@@ -124,7 +124,7 @@ class Lu
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/par_ic.hpp b/include/ginkgo/core/factorization/par_ic.hpp
index 1b49ce83edc..06288190785 100644
--- a/include/ginkgo/core/factorization/par_ic.hpp
+++ b/include/ginkgo/core/factorization/par_ic.hpp
@@ -139,7 +139,7 @@ class ParIc : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/par_ict.hpp b/include/ginkgo/core/factorization/par_ict.hpp
index 9d0b194a69a..509a7455051 100644
--- a/include/ginkgo/core/factorization/par_ict.hpp
+++ b/include/ginkgo/core/factorization/par_ict.hpp
@@ -188,7 +188,7 @@ class ParIct : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/par_ilu.hpp b/include/ginkgo/core/factorization/par_ilu.hpp
index 1497b8c3574..0db06813e79 100644
--- a/include/ginkgo/core/factorization/par_ilu.hpp
+++ b/include/ginkgo/core/factorization/par_ilu.hpp
@@ -137,7 +137,7 @@ class ParIlu : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/factorization/par_ilut.hpp b/include/ginkgo/core/factorization/par_ilut.hpp
index 24136b089a8..aa1948c6b8d 100644
--- a/include/ginkgo/core/factorization/par_ilut.hpp
+++ b/include/ginkgo/core/factorization/par_ilut.hpp
@@ -194,7 +194,7 @@ class ParIlut : public Composition<ValueType> {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/preconditioner/ic.hpp b/include/ginkgo/core/preconditioner/ic.hpp
index e505d04731e..01364424a76 100644
--- a/include/ginkgo/core/preconditioner/ic.hpp
+++ b/include/ginkgo/core/preconditioner/ic.hpp
@@ -164,7 +164,7 @@ class Ic : public EnableLinOp<Ic<LSolverType, IndexType>>, public Transposable {
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/preconditioner/ilu.hpp b/include/ginkgo/core/preconditioner/ilu.hpp
index 3174b31cf0e..a94ee930946 100644
--- a/include/ginkgo/core/preconditioner/ilu.hpp
+++ b/include/ginkgo/core/preconditioner/ilu.hpp
@@ -207,7 +207,7 @@ class Ilu : public EnableLinOp<
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/preconditioner/isai.hpp b/include/ginkgo/core/preconditioner/isai.hpp
index 8d3fb044d49..4ef5b7da7d3 100644
--- a/include/ginkgo/core/preconditioner/isai.hpp
+++ b/include/ginkgo/core/preconditioner/isai.hpp
@@ -197,7 +197,7 @@ class Isai : public EnableLinOp<Isai<IsaiType, ValueType, IndexType>>,
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *
diff --git a/include/ginkgo/core/preconditioner/jacobi.hpp b/include/ginkgo/core/preconditioner/jacobi.hpp
index f6ee3de5de1..f5adbd94651 100644
--- a/include/ginkgo/core/preconditioner/jacobi.hpp
+++ b/include/ginkgo/core/preconditioner/jacobi.hpp
@@ -503,7 +503,7 @@ class Jacobi : public EnableLinOp<Jacobi<ValueType, IndexType>>,
 
     /**
      * Create the parameters from the property_tree.
-     * Because this is directly tied to the specific type. The value/index type
+     * Because this is directly tied to the specific type, the value/index type
      * settings within config are ignored and type_descriptor is only used
      * for children objects.
      *